JPH0763607A - Foreign matter detection sensor - Google Patents

Abstract

PURPOSE:To enlarge depth of field as well as to detect small foreign matter by providing a light-conduction section that forms a plurality of elongated light-conduction passages and a photo-detection section that detects intensity of light. CONSTITUTION:The photo-detection section 3 consisting of image-pickup elements such as CCD or the like detectors each of the intensity of lights inputted via respective light-conduction passages of a light-conduction section 2 and converts the light to an electric signal to transmit it to an amplifier 4. The amplifier 4 amplifier the electric signal obtained by the photo-detection section 3 to transmit it to a recorder 5. The recorder 5 records the electric signal obtained by the photo-detection section 3. A light from a light source A is on an extending line of the center axis of a cylindrical body 2A so that it is detected by the photo-detection section 3 via the conductive passage 2b. On the other hand, a light from a light source B is not on the extending line of the center axis of the cylindrical body 2A so that the light does not pass the conductive passage 2b and is not detected by the photo-detection section 3. A sensor that detects the light passing each of the cylindrical bodys 2A by means of the photo- detection section 3, is so constituted that a plurality of cylindrical bodies 2A are bundled in parallel, thereby detecting an object without being influenced by depth of field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter detection sensor for detecting an object by an optical observation means.

[0002]

2. Description of the Related Art Generally, a foreign matter detection sensor for optically observing an object (observed object) such as a foreign matter forms an image of the object on the surface of an image pickup device such as a CCD (Charged Coupled Device) or a photoelectric tube through a plurality of lenses. An image is formed, and the formed image is taken out as an electrical signal by the image pickup device. Moreover, what is called a line sensor can be interpreted as a one-dimensional array of such image pickup devices.

Using such a line sensor, for example, as a means for detecting foreign matter passing through the inside of a pipe filled with liquid, a transparent window is provided in this pipe, and light is emitted from the outside of this window. Then, a method of detecting the presence of foreign matter in the pipe can be considered. However, with such means,
Due to the depth of field of the lens of the line sensor, the lens is not focused on the foreign matter passing through the pipe, and it is practically difficult to detect the small foreign matter over the entire cross-sectional area of the pipe. For this reason, the lens is provided with a diaphragm, and by narrowing it down, the depth of field is set large.

[0004]

However, when trying to detect the presence of a small foreign substance by narrowing down the diaphragm of the lens, before and after the focus with the highest resolution,
There is a problem that the size of the smallest detectable foreign matter changes in the portion where the resolution is lowered away from that. For this reason, it is difficult to detect a small foreign matter in the portion away from the focal point of the lens. Further, in order to accurately detect the size of the foreign matter, the focal length must be set long for the above-mentioned reason, and there is a problem that the line sensor becomes large.

The present invention effectively solves the above problems, and an object of the present invention is to provide a foreign matter detection sensor capable of setting a large depth of field and detecting even a small foreign matter.

[0006]

A foreign matter detection sensor of the present invention is provided with a light guide portion having a plurality of elongated light guide paths each having a light introduction port at its tip and a rear end side of the light guide portion. And a light receiving unit for detecting the intensity of light incident through each of the light guide paths. The light guide path may be provided with a lens for focusing the light introduced from the tip of the light guide path on the light receiving section.

[0007]

In the foreign matter detection sensor of the present invention, light is introduced into each of the plurality of light guide paths, and the light of each light guide path is detected separately by the light receiving section, so that foreign matter corresponding to the size of the light guide path is reliably detected. Can be detected. Further, when the foreign matter moves, the intensity of light passing through each light guide path is generated along the movement state, and therefore the movement of the foreign matter can be captured by capturing the intensity of this light. Further, when the lens is provided in the light guide path, the introduction of the light from the oblique outer side of the tip of the light guide path is restricted, so that the light from the oblique outer side is not detected and the detection sensitivity is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the foreign matter detecting sensor of the present invention will be described below with reference to FIGS. As shown in FIG. 1, reference numeral 1 denotes a foreign matter detection sensor. The foreign matter detection sensor 1 includes a light guide section 2 including a plurality of cylindrical bodies 2A bundled in a parallel state, and the light guide section 2. The light receiving unit 2 provided at the rear end portion, the amplifier 4 connected to the light receiving unit 2, and the recorder 5 for recording the result of the amplifier 4 are provided, and the internal space of the light guiding unit 2 is a light guide path. 2b is formed.

Although the light guide section 2 is an assembly of cylindrical bodies 2A, one in which a large number of holes are formed by etching or machining to form a light guide path for each hole is used. May be. The inner peripheral surface of each cylindrical body 2A of the light guide section 2 is made of a material or a shape with less reflection. An introduction port 2a for introducing light to the light guide path 2b is formed at the front end portion of the light guide portion 2, and a light receiving portion 3 for detecting the light emitted from each light guide portion 2 is attached at the rear end portion thereof. Has been.

The light receiving section 3 is composed of an image pickup device such as a CCD, detects the intensity of light incident through each light guide path 2b of the light guide section 2, and converts this light into an electric signal. Then, the electric signal is transmitted to the amplifier 4. The amplifier 4 amplifies the electric signal obtained by the light receiving unit 3 and transmits the amplified electric signal to the recorder 5. The recorder 5 records the electric signal obtained by the light receiving unit 3.

Each light guide portion 2 of such a foreign matter detection sensor 1
The detection principle of will be described with reference to FIG. As shown in FIG. 2, since the light from the light source A is disposed on the extension line of the central axis of the cylindrical body 2A, the light from the light source B passes through the light guide path 2b and is detected. Is not arranged on the extension line of the central axis of the cylindrical body 2A, it does not pass through the light guide path 2b and is not detected by the light receiving section 3. Such a tubular body 2
By bundling a plurality of A's in a parallel state, the foreign matter detection sensor 1 for detecting the light passing through each of the tubular bodies 2A by the light receiving unit 3 is configured.

Next, using this foreign matter detection sensor 1, as shown in FIG.
The case of detecting the foreign matter D in the water tank 10 as shown in FIG. As shown in FIG. 1, the introduction port 2 a of the light guide unit 2
When the foreign matter D exists in the water tank 10 in front of the water tank 10, light is emitted from the opposite side to the installation position of the foreign matter detection sensor 1 and the scattered light of this light is detected. That is, the region where the light is blocked by the foreign matter D and the light passing through the water tank 10 in the state where the light is not blocked by the foreign matter D are detected for each tubular body 2A.

Here, since the diameter is formed sufficiently smaller than the length of the tubular body 2A, the inlet 2a of the tubular body 2A is formed.
Even if the foreign matter D is installed at a position away from the foreign matter D, the foreign matter D existing on the extension line of the central axis of each tubular body 2A
Is reliably detected. Therefore, by passing light through each of the cylindrical bodies 2A that are bundled in a plurality of parallel states, the foreign matter D
Is detected two-dimensionally. Image processing is performed on the detection result, and the size and number of the foreign matter D are counted.

At this time, since the resolving power of the portion away from the light guide portion 2 is poor, it is preferable to form the light guide path 2b sufficiently long. If the light guide path 2b is formed sufficiently long, the foreign matter detection sensor 1 having high resolution can be obtained. When detecting a foreign substance from the flow passage in the pipe, the light guide unit 2 is installed at a right angle to the flow passage of the pipe, and the number of foreign substances passing through the cross section of the pipe is continuously observed. May be. And
The foreign matter detection sensor 1 may be installed parallel to the flow path in the pipe, and the light receiving unit 3 of the foreign matter detection sensor 1 may be rotated about the axis of the pipe to detect the foreign matter.

According to such a foreign matter detection sensor 1, a light guide section 2 having a plurality of elongated light guide paths 2b each having a light introduction port 2a at its tip and a rear end side of the light guide section 2 are provided. Each of the light guide paths 2b is provided with a light receiving section 3 for detecting the intensity of light incident through each of the light guide paths 2b.
Light can be passed through the inlet 2a for each b and detected by the light receiving unit 3. Therefore, light in a region that is not on the extension line of the central axis of the light guide path 2b is not imaged on the light receiving section 3, and only the region on the extension line of the center axis of the light guide path 2b can be imaged on the light receiving section 3, and Objects can be detected without being affected by the depth of field. Therefore, the aperture of the lens and the like can be eliminated, the resolution of the light receiving portion can be maintained, and the aperture of the lens can be eliminated, so that the resolution of the light receiving portion 3 can be maintained and the need to set a long focal length is eliminated. Therefore, it is possible to prevent the foreign matter detection sensor from increasing in size.

<Second Embodiment> A second embodiment of the foreign matter detecting sensor of the present invention will be described with reference to FIG. As shown in FIG. 3, in the foreign matter detection sensor of the second embodiment, a lens 7 is installed in the introduction port 2a of the light guide unit 2, and other configurations are the same as those of the foreign matter detection sensor of the first embodiment. There is. The lens 7 corresponds to the entire length 1 of the light guide section 2 with respect to the light receiving section 3
It is installed at the focal length for imaging.

As described above, by providing the lens 7 in the light guide 2b of the light guide 2 for focusing the light introduced from the tip of the light guide 2b on the light receiver 3, the lens 7 is extended to the central axis of the lens 7. Areas that are not on the line are not imaged on the light receiving unit 3, and light introduced from the extension line of the central axis of each lens 7 can be imaged on the light receiving unit 3. Therefore, the light reaching the light receiving unit 3 is decomposed by the lens 7, so that the resolution of the foreign matter detection sensor can be improved. Then, a lens 7 is provided at the inlet 2a of the light guide portion 2 and light is imaged on the light receiving portion 3 by this lens 7, so that light from an oblique direction with respect to the central axis of the tubular body 2A is not detected. .

According to such a foreign matter detection sensor, since the light guide path 2b is provided with the lens 9 for focusing the light introduced from the tip of the light guide path 2b on the light receiving portion 3, the center axis of the light guide path 2b is located. On the other hand, the light from the oblique direction is not imaged, and the light on the extension line of the central axis of the light guide path 2b is imaged on the light receiving unit 3.
Therefore, the light reaching the light receiving unit 3 can be decomposed by the lens 9, and the resolution of the foreign matter detection sensor can be improved.

<Third Embodiment> A third embodiment of the foreign matter detecting sensor of the present invention will be described with reference to FIG. As shown in FIG. 4, in the foreign matter detection sensor of the third embodiment, a lens 9 is attached in the middle of the light guide portion 2, and the other configurations are similar to those of the foreign matter detection sensor of the first embodiment. The lens 9 is set to a focal length for forming an image of light on the light receiving unit 3 with respect to the length 1 of the lens 9 and the light receiving unit 3 in the light guide unit 2.

Since the lens 9 is provided in the light guide path 2b of the light guide section 2 in this way, the light passing through the light guide section 2 passes through the lens 9 and the light is imaged on the light receiving section 3 by the lens 9. It Therefore, an area that is not on the extension line of the central axis of the light guide path 2b is not imaged, and further, light from an oblique direction with respect to the central axis of the lens 9 is not imaged on the light receiving section 3. Therefore, the resolution of the foreign matter detection sensor can be improved. Although the lens 9 is installed near the center of the light guide 2 in the figure,
The lens 9 may be installed near the light receiving unit 3.

[0021]

As described above, according to the foreign matter detection sensor of the present invention, the following effects can be obtained. According to the foreign matter detection sensor of claim 1, a light guide portion having a plurality of elongated light guide paths each having a light introduction port at its tip,
Since the light guide section is provided at the rear end side of the light guide section and detects the intensity of the light incident through each of the light guide paths, the light is passed through each light guide path. It can be detected by the light receiving part. Therefore, the light in the area that is not on the extension line of the central axis of the light guide path is not imaged on the light receiving section, and only the area on the extension line of the central axis of the light guide path can be imaged on the light receiving section, which affects the depth of field. The object can be detected without being detected. Therefore, it is possible to eliminate the need for a lens diaphragm, etc., and to maintain the resolution of the light receiving unit,
It is possible to eliminate the need for a long focal length and prevent the foreign matter detection sensor from becoming large.

According to the foreign matter detection sensor of claim 2,
Since the light guide path is provided with a lens for focusing the light introduced from the tip of the light guide path on the light receiving section, only the region on the extension line of the central axis of the lens is imaged on the light receiving section, and An area that is not on the extension line of the central axis is not imaged on the light receiving portion. For this reason, since the light is decomposed by the lens together with the light guide path, the resolution of the foreign matter detection sensor can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a foreign matter detection sensor of the present invention.

FIG. 2 is a configuration diagram for explaining a light guide unit in FIG.

FIG. 3 is a configuration diagram showing a light guide section of a second embodiment of the foreign matter detection sensor of the present invention.

FIG. 4 is a configuration diagram showing a light guide section of a third embodiment of the foreign matter detection sensor of the present invention.

[Explanation of symbols]

 1 foreign matter detection sensor 2 light guide 2a inlet 2b light guide 3 light receiver

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G02B 6/00 // G01N 21/47 Z 9118-2J

Claims (2)

[Claims] 1. A light guide section having a plurality of elongated light guide paths each having a light introduction port at its tip, and one light guide section provided at the rear end side of the light guide section. A foreign matter detection sensor, comprising: a light receiving section for detecting the intensity of incident light. 2. The foreign matter detection sensor according to claim 1, wherein the light guide path is provided with a lens that images the light introduced from the tip of the light guide path onto the light receiving section.